1. Field
This invention pertains to hearing testing and hearing aid fitting devices. In particular it pertains to a hearing testing device employing means of extrapolated distortion product otoacoustic emission input/output functions (DPOAE I/O-functions) and/or auditory brain stem responses (ABRs) as well as for automatically fitting hearing aids without any cooperation of the subject tested using a device having a display screen attached to a handheld device generating and collecting otoacoustic emission signals and/or brain stem response signals into a programmed computer with a clinical audiogram providing fitting parameters for hearing aids calculated on the basis of assessed hearing threshold and compression. In addition tympanometry and ABR-Inter-Peak-Latency assessment (ABR-IPL) for differentiating middle-ear, cochlear and neural disorders can be optionally performed.
2. State of the Art
Psychoacoustical tests are commonly used for assessing hearing threshold. These tests are not successful with patients that cannot communicate responses, such as neonates, and require skilled testers who can interpret the responses. Furthermore, psychoacoustical tests need a lot of time to assess disturbances of sound processing. As a result, objective measurements for assessing hearing loss have been developed. Conventionally, behavioral hearing threshold is represented as hearing loss in a clinical audiogram form at different frequencies, usually at 125, 250, 500, 1000, 2000, 4000, and 8000 Hz. In principal, also ABRs and OAEs are potential measures for assessing hearing loss. The advantage of these measures over behavioral hearing testing is that they are “objective” in the sense that no cooperation of the patient is needed, and therefore can be used in infants and young children. Furthermore, objective measurements allow more precise identification of hearing impairment in a shorter time. Thus, they are also suited for hearing testing in adults. Behavioral threshold and the latency and amplitude of ABRs and the distortion product otoacoustic emission (DPOAE) sound pressure level and the slope of the DPOAE I/O-function, respectively, are reported to be closely related (Jacobson 1985, Janssen et al. 1998, Kummer et al. 1998). Various measurements devices have been employed to measure these responses. However, they also require trained testers, and elaborate equipment. The device and method described below provides an easy to use handheld hearing testing device, which also provides hearing aid fitting parameters which are calculated on the basis of the assessed loss of hearing and compression. The fitting of the hearing aid is performed automatically after identifying the type of the hearing aid and loading the respective software for adjusting the hearing aid.